1. Field of the Invention
The present invention relates to a semiconductor device and a method of fabricating thereof. More particularly, the present invention relates to a semiconductor device and fabricating method thereof capable of improving negative bias temperature instability (NBTI) of the PMOS used as a input/output (IO) device.
2. Description of the Related Art
In the matter of the function, the semiconductor devices can be mainly distributed into IO devices and core devices. In accordance with electrical type of the devices, the IO devices further include a IO PMOS and a IO NMOS, wherein the IO PMOS represents a PMOS used as a IO device and the IO NMOS represents a NMOS used as a IO device. The core devices similarly include a core PMOS and a core NMOS.
The use of strained silicon has been utilized to improve the performance of the core device, but this manner is profitless to the reliability of a IO PMOS. Furthermore, the higher voltage is applied to the IO devices, especially the IO PMOS, so NBTI of the IO PMOS can not be reduced and thus the performance and reliability of the IO devices cannot be improved.